By Dr Ananya Mandal, MD
According to a new study babies fed starchy table foods, which often contain added salt, before 6 months of age show a preference for salt that persists through their preschool years.
Infants who had been introduced to starchy foods preferred a saltier drink and drank 55% more of the saltier drink during a test at 6 months of age say researchers. By the time they were preschoolers, the same children were also more likely to lick the salt from foods and eat plain salt.
Researchers say the results suggest the ability to detect salty taste matures sometime between 2-6 months of age. â€œThere could be quite a bit of difference in how that taste for salt matures, depending on whether or not an infant is exposed to sodium during that period,â€ says researcher Leslie Stein, senior research associate at the Monell Chemical Senses Center in Philadelphia.
Studies have shown that too much sodium, often in the form of salt, is associated with an increased risk of high blood pressure. Curbing salt intake has been a major public health goal for years, but researchers say efforts thus far have been largely unsuccessful, in part because people like the taste of salt. Nearly 90% of Americans consume more sodium per day than is recommended, according to an October report from the Centers for Disease Control and Prevention. In recent years, public-health officials have increasingly urged Americans to reduce their sodium consumption and have encouraged food companies to scale back the sodium they use, but these messages have gone largely unheeded. Some food manufacturers have been reluctant to use less sodium for fear of losing customers to saltier competitors.
In the study, published in the American Journal of Clinical Nutrition, researchers tested a group of 61 infants at 2 months and 6 months of age for salt preference by measuring how much they drank from three different bottles. One bottle contained plain water, another contained a moderately salty concentration of sodium (about the saltiness of commercial chicken soup), and a third contained a higher concentration of sodium (which tastes extremely salty to adults).
Results showed that 2-month-old infants were indifferent or rejected the salt solutions. But at 6 months of age, the infants who were already eating starchy table foods preferred both salty solutions to water. The babies that had not yet been introduced to these foods were still indifferent or rejected the salt solutions. Exposure to other types of table foods, such as fruits and vegetables, was not associated with an increased preference for salt.
Years later, the mothers of the 26 children returned for questioning about their childâ€™s eating habits as preschoolers between ages 3 and 4. Researchers found that 12 preschoolers who were introduced to starchy foods before 6 months of age were more likely to lick salt from foods like pretzels and crackers and were also slightly more likely to eat plain salt.
â€œWhat our study shows is that babiesâ€™ taste system is very malleable,â€ Stein says. â€œIf early exposure to salt increases the preference and taste for salt of an individual, then one might imply that down the road it might be harder to eat lower-salt food and enjoy it.â€ â€œOur findings suggest that early dietary experience influences the preference for salty taste,â€ he says.
He said, â€œExperimental studies are now needed to address the important question of how children and adults come to prefer high levels of salt in their food.â€ Previous research by Bristol University showed seven in ten babies are getting too much salt from a diet of processed foods such as gravy, baked beans and tinned spaghetti - increasing their risk of health problems in later life. A study of almost 1,200 infants found almost 70 per cent consumed more than double the maximum recommendation of salt for that age group, which is just one gram of sodium per day.
â€œThis study helps us appreciate that what we do in the first year of life is so important to how kids eat, how well they eat, how varied they eat, and what their food preferences are,â€ says pediatric nutritionist Jill Castle. She advises that between 6 months and 8 months of age, babies should only be just starting to be exposed to starchy table foods like bread, crackers, and ready-to-eat cereals in small amounts. The bulk of their daily calories should still come from breast milk or formula, iron-fortified baby cereal, fruit, and vegetables.
â€œIn Paleolithic times infants had breast milk for two to three years, but in modern culture, many kids go to processed foods, where the factory decides how much salt to put in,â€ says Philip J. Klemmer, a professor of medicine at the University Of North Carolina School Of Medicine, in Chapel Hill, who was not involved in the new research. The way the babies in the study seem to have developed a taste for salt is â€œalmost like imprinting,â€ Klemmer says, referring to the process by which infants bond with their parents and learn other social behaviors.
â€œThere seems to be an increased preponderance of parents trying to choose those types of foods for their kids,â€ says pediatrician Christine Wood. â€œThese foods are being marketed as being appropriate for children, but I really try to focus in on parents trying to have the focus on a lot of fresh foods, fruits, and vegetables being the most important things.â€ Aside from increasing the risk of high blood pressure and heart disease down the road, Wood says there are also more immediate health risks associated with children developing a taste for salty foods. â€œWe know that starchier foods in general are more calorie-dense foods,â€ says Wood that may lead to a higher risk of childhood obesity.